Adding the 8061 date format which was referenced in L65 comment but not actually implemented

Author: berglh

patterns/grok-patterns

@@ -65,10 +65,11 @@ TIME (?!<[0-9])%{HOUR}:%{MINUTE}(?::%{SECOND})(?![0-9])
 # datestamp is YYYY/MM/DD-HH:MM:SS.UUUU (or something like it)
 DATE_US %{MONTHNUM}[/-]%{MONTHDAY}[/-]%{YEAR}
 DATE_EU %{MONTHDAY}[./-]%{MONTHNUM}[./-]%{YEAR}
+DATE_8061 %{YEAR}[./-]%{MONTHDAY}[./-]%{MONTHNUM}
 ISO8601_TIMEZONE (?:Z|[+-]%{HOUR}(?::?%{MINUTE}))
 ISO8601_SECOND (?:%{SECOND}|60)
 TIMESTAMP_ISO8601 %{YEAR}-%{MONTHNUM}-%{MONTHDAY}[T ]%{HOUR}:?%{MINUTE}(?::?%{SECOND})?%{ISO8601_TIMEZONE}?
-DATE %{DATE_US}|%{DATE_EU}
+DATE %{DATE_US}|%{DATE_EU}|%{DATE_8061}
 DATESTAMP %{DATE}[- ]%{TIME}
 TZ (?:[PMCE][SD]T|UTC)
 DATESTAMP_RFC822 %{DAY} %{MONTH} %{MONTHDAY} %{YEAR} %{TIME} %{TZ}